Production of filaments, yarns, fabrics, and like materials



Patented Sept. 8, 1936 char e states IPRODUQ'JTION OF FFLAMENTS, YARNS,FABRICS, AND LEKE MATERIALS Henry Dreyfus, London, England No Drawing.Application February 8, 1933,

Serial No. 655,774. 19,1932

4 Claims.

This invention relates to improvements in the production of filaments,yarns, fabrics and like materials, and is directed to the production offilaments, threads, yarns and the like, or fabrics or like materialscontaining the same, which consists of or substantially consist ofregenerated cellulose, or which at least have an aifinity for the cottoncolours, and which have a high tenacity.

In recent years considerable attention has been directed to theproduction of filaments, threads and yarns of artificial silk, andparticularly of artificial silk oi the viscose or regenerated cellulosetype, which have high, dry and wet tenacities, and in particular drytenacities of 3 to 5 grams or more per denier. While some success hasbeen achieved in. the production of such yarns, nevertheless theprocesses involved in their production present considerabledisadvantages, and the products, while possessing high tenacities, havedisadvantages which may cutweight this advantage. In general theseprocesses have involved the use at some stage of concentrated acids. Notonly are such acids diflicult to work with on a commercial scale, but inaddition they involve the use of expensive apparatus, and moreover ingeneral yield products which possess the serious disadvantages of beingbrittle and lacking the flexibility desirable in textile products. Thepresent invention aims to produce filaments, threads, yarns and the likeand fabrics containing the same which have high tenacities or at leasthigher tenacities than ordinary viscose silk and are of the regeneratedcellulose type, or consist substantially of regenerated cellulose, or atleast have an affinity for the cotton colours.

The prior processes referred to involve the use of aqueous spinningsolutions, and notably solutions of viscose as the starting material.The present invention, on the other hand, uses as starting materialcellulose acetate or other organic esters of cellulose.

I have found that products of the character referred to may be obtainedby saponification of filaments, threads, yarns, or fabrics containingthe same,.made of or containing cellulose acetate or other organicesters of cellulose of high viscosity characteristics. Thus thecellulose acetate used should have a viscosity exceeding 30 as measuredby comparing the rate of flow of a 6% solution in acetone at 25 C.against a standard of glycerine taken as-100. Yarns of such celluloseacetate or other organic esters of cellulose may have a relatively hightenacity, for example in Great Britain February (Cl. 8-2ll) a tenacityexceeding 1.5 grams per denier, and

preferably exceeding 2 grams per denier. The

best results are obtained according to the present invention bysaponifying yarns of a cellulose acetate having a viscosity exceeding 50and, still better, of the order of 75, 100, 150 or 200 or more on theabove scale. The saponiiication of yarns and other materials containingcellulose acetate by means of caustic soda or caustic potash has beenknown for many years, but in general the application of suchsaponification processes to the ordinary cellulose acetate yarns resultsin a decrease, and in some cases a very serious decrease, in the drytenacity of the yarn under treatment. In the present invention, on theother hand, it is found that provided the conditions of saponificationare not unduly drastic the tenacity of the high viscosity yarn may notonly be maintained but may even increase very considerably as a resultof the saponification treatment. This is a very remarkable observation,since owing to the fact that high viscosity yarns of cellulose acetateor other organic esters of cellulose are somewhat less amenable tosaponification than ordinary yarns, and hence have to be 25 subjected toconditions during saponification which are somewhat more drastic thanthose applicable to ordinary yarns to obtain a similar degree ofsaponification, or have to be subjected to the ordinary conditions forlonger periods, it would be expected that as a result the tenacity, farfrom being increased by the saponification treatment, would be decreasedto a still greater extent than in the case of ordinary yarn. Again whilein the treatment of ordinary yarn with 7 caustic alkalies for thepurpose of saponification particular attention has been paid torestricting the concentration of alkali, for example to under 1%solution, for the purpose of maintaining as far as possible thetenacity, it is found that in 40 the treatment of high viscosity yarnsaccording to the present invention concentrations considerably above l%.may be applied, and still substantial increases in tenacity areobtained. Thus, concentrations of 5% or more of caustic soda andtemperatures up to 90 C. have been used with success and yield productsof relatively high tenacity.

The high viscosity cellulose acetates or other cellulose esters may beproduced by any suitable methods and particularly methods involvingaminimum of degradation of the cellulose molecule. In this connection Iparticularly refer to the process of my U. S. Patent No. 1,708,787, inwhich esterification is effected in presence of large bulk of solventfor the ester produced and particularly a weight of solvent exceeding 6or 8 times that of the cellulose undergoing esteriflcation.

The high viscosity filaments, yarns, threads or the like may be producedby wet or dry-spinningapplied to the materials, the process is includedin my co-pending U. S. application S. No. 655,775 filed February 8,1933. Dry spinning of the high viscosity cellulose esters may beeffected, for example, by the processes and apparatus of U. S. PatentsNos. 1,601,125, 1,731,317, 1,541,104, 1,814,468 and 1,934,618.

The saponification treatment. may be carried out by means of anysuitable basic reagent. The most important for this purpose are causticsoda and caustic potash. When using caustic soda or caustic potash inaqueous solution or in mixed aqueous-alcoholic solution it is advisable,particularly when the concentration of the caustic alkali is relativelyhigh, for example over 1% to include in the saponifying medium a bufiersalt, for example sodium chloride, sodium acetate, or sodium salts ofother fatty acids, including the soaps or sodium salts of higher fattyacids, or other substance adapted to repress any destructive actionwhich the caustic alkali may have upon the cellulose material undertreatment. Thus, it is highly advantageous to have present in thesaponifying medium sodium chloride in a high concentration, for examplein a concentration of 20%-25% or more depending upon the solubility ofthe sodium chloride at the temperature of the saponification treatment.Sodium acetate may be dissolved in similar high concentrations. In factit is of great advantage to use as a bufier salt in the saponifyingmedium the salt which is produced by the action of the saponifyingagent, for instance caustic soda, upon the cellulose ester, for instancecellulose acetate, since such a salt is always present in the spentsaponifying liquor, and its use as a bufier salt considerablyfacilitates regeneration of the spent liquor. the caustic alkali in theaqueous or aqueousalcoholic medium may be adjusted in accordance withthe required degree of saponification, the temperature used-in thesaponification and the time available for treatment. I have obtainedvery good results by employing as saponifying medium a 4-5 or even 5 -6%solution of caustic soda in a 25% aqueous solution of sodium chloride orsodium acetate at temperatures ranging from 75-90 C., the time oftreatment being of the order of 1 minute, this time being very suitablefor treatment of travelling filaments, threads or yarns in a bath at aspeed of about 40 metres per minute. Again good results are obtainableby employing concentrations of the order of 10-12% caustic soda orcaustic potash together with about 18% of sodium chloride or as muchsodium chloride as will dissolve in the caustic alkali or correspondingconcentrations or even higher concentrations of sodium or potassiumacetate at temperatures ranging from 7590 C., the time of treatmentbeing correspondingly shorter, for example of the order of 20 seconds.This treatment may be applied with filaments, threads or yarnstravelling in a bath at a speed of the order The concentration of ofmetres per minute. However, the invention is not limited to thesespecific concentrations, and the caustic soda may be used in lowerconcentrations preferably at higher temperat .lres or in higherconcentrations preferably a lower temperatures.

The application in a bath treatment of relatively high concentrations ofcaustic alkali, i. e. concentrations of about 2% or over, rangingupwards to 10-12 or even 15% or more, particularly when combined withthe use of high concentrations of buffer substances, for instance sodiumor potassium chloride or acetate or soaps, for example concentrations ofbuffer substances of the order of 10%, and particularly 15-25%, or tosaturation, at high temperatures, and particularly temperatures above 65C. up to the boiling point, for example the temperature range mentionedabove of 75-90 C. for relatively short periods, such as periods rangingfrom 10 seconds to 1 minute, constitutes an entirely new saponificationprocess, and is applicable not only to high viscosity filaments,threads, yarns and other products with which the present invention isparticularly concerned, but also to materials containing esters of low,ordinary or any other viscosity, for example ordinary dry-spun celluloseacetate yarn, with highly satisfactory results. As with the highviscosity yarn a bath saponification under these conditions, contrary toall expectation, may result not only in maintenance of the initialtenacity of the yarn or other material, but in a substantial increase inthe tenacity. The invention therefore includes the application of thesesaponification conditions in a bath treatment whatever be the characterof the textile material under treatment. Thus, the cellulose estercontained in the textile material may be of any viscosity, for examplerelatively low viscosities of 6-10 or ordinary viscosities of 10P-20 or30 or high viscosities of 40 or 50400 or 200 or more are measured bycomparing the viscosity of a 6% solution of the cellulose acetate inacetone at a temperature of 25 C. with that of glycerine at the sametemperature taken as a standard of 100. Further, the yarn or othermaterial may be stretched or unstretched. In this special process,instead of using the above concentrations 01' caustic alkali solutions,other alkaline substances, for instance sodium silicate, trisodiumphosphate, may be used in concentrations giving similar degrees ofalkalinity.

In addition to including saponification by caustic alkali in aqueous oraqueous-alcoholic media the invention further includes saponification ina purely alcoholic medium. As is known in such a process the causticsoda may be present in the alcoholic medium, for example in a medium oimethyl or ethyl alcohol, in a proportion less than that theoreticallyrequired to produce the required degree of saponification. Thus, inorder to produce substantially complete saponification the caustic sodamay be present, for example, in a proportion ranging from about 13-35%or more of that theoretically necessary to eliminate all the estergroups. The concentration of the caustic alkali in the alcoholic mediummay vary very considerably, for example from the very low concentrationof under .05% to 5% or more. The saponification in a purely alcoholicmedium may be eilected at atmospheric temperature or at any convenienthigher temperature. In this method of carrying out the saponification itis, however, of great advantage to effect the saponification atrelatively low temperatures and to allow the samedia.

ponifying medium to act for a considerable time so that this processlends itself more particularly to batch processes in which, for example,the yarns, threads or the like are treated in the form of hanks orcakes. Similarly instead oi employing methyl alcohol or ethyl alcohol asthe medium in which to dissolve the saponiiying agent other alcoholic oreven phenolic media may be employed, for example monohydric alcoholshigher in the series than ethyl alcohol, or dior polyhydric alcohols,for example the glycols, glycerine or the like. With the highermonohydric alcohols and still more with the diand polyhydric alcoholsthe best results are obtained at temperatures exceeding atmospheric, forexample temperatures of the order of 50-80 or even C. Highertemperatures do not in general lead to the best results according to thepresent invention. The term alcoholic medium is to be understood toinclude the use as medium of certain cyclic alcohols. As alreadyindicated, phenolic media may be used, but it is desirable to use thephenols in very low concentration in aqueous solution and to employrelatively low temperatures.

While in the above description caustic soda and caustic potash havealone been referred to as the saponifying agents, the invention is notlimited to these agents, but includes quite broadly the use of alkalinesaponifying agents. Other suitable agents include sodium silicate,trisodium phosphate and ammonia. Such reagents may be applied inaqueous, alcoholic or aqueous-alcoholic Ammonia or volatile organicamines may be used in the vapour state, particularly when mixed withsteam or water vapour to effect the saponification.

The saponifying mixture may be applied to the threads by any suitablemethod, for example by bath treatments, padding methods particularlyfollowed by a batching process during which the saponifying mixture hastime to effect the requisite degree of saponiflcation, spraying methodsfollowed by batching, gaseous or vaporous application of the saponifyingagent as previously referred to, or the methods described in U. S.Patents Nos. 1,884,622 and 1,884,623 in which the saponifying mixture isapplied to the materials and immediately afterwards the materials areheated, for example by passage over heated drums or like devices toefiect a quick saponification. In methods involving batching orsubsequent heating to efiect saponification, the concentration in whichthe caustic alkali or other saponifying agent is applied is relativelyimmaterial provided that there is enough of the medium to enable uniformapplication of the saponifying agent.

The extent of the saponification may vary considerably depending uponthe object in view. An afiinity for the cottom colours is acquired witha comparatively small loss in weight, such as 5-10 or 20%, though suchlow degrees of saponification are in general only effective inconferring amnity for the cotton colours when the saponification ismainly superficial. If, as in the case of using an alcoholic medium forthe saponii'ying agent, the saponification is relatively uniform, asomewhat higher degree of saponification, for example up to 50% or moreof the ester groups, is generally necessary to confer aflinity for thecotton colours. The invention particularly contemplates complete orsubstantially complete elimination of the ester groups, since, asalready indicated. the main object of the invention is to producefilaments, yarns, threads or the like which are of high tenacity and areof the regenerated cellulose type.

. of threads.

The best method of carrying the present invention into effect is to usea bath saponifying treat ment and to treat a warp or yarns in oneoperation. It is found that great advantages accrue from treating thetravelling threads, particularly when travelling in the form of a warpor sheet Thus, the threads from a creel of bobbins may be carriedthrough a reed, round one or more rollers, for example nip rollers orfeed rollers, into the saponifying bath, preferably through a furtherreed, traverse an appropriate length of bath, the length depending uponthe desired degree of saponification, the speed of trave1, thetemperature of the bath and the concentration and character of thesaponifying agent, then through a further reed, round a feed roller, outof the bath and finally to a washing device, and preferably to a dryingand reeling or beaming device. It is desirable in order to utilize thefull length of the saponifying bath to wet out the materials thoroughlyeither on entering the saponifying bath or before entering. For thispurpose the yarns may be carried into a short wetting out bath in whichthey are carried through a pair of nip rollers, one at least of whichdips into a wetting out liquid. The nip rollers are preferably soarranged that one is in advance of the other so that their rotationcauses a trough of liquid to collect in the nip of the rollers. By thismeans very emcient wetting out may be obtained. The rollers may be metalrollers or may be covered with fabric or with rubber or similarmaterials to assist wetting out. The wetting medium may be water, or maybe an aqueous solution of a wetting agent, as for example the soaps, forexample sodium potassium or ammonium oleates, palmitates or stearates,sulphonated soaps, for example Turkey red oil or Monopol soap, thenaphthalene sulphonic acid wetting agents, and particularly the propyland butyl naphthalene sulphonic acids or their salts, or theu-amino-alkylamides of oleic, stearic, palmit'ic or other fatty acids. Asmall proportion of the saponifying agent itself may be included in thewetting out bath.

Instead of applying a continuous treatment as described above, batchtreatments, for example with the yarn in the form of hanks or cakes maybe applied. Such batch processes are particularly useful where it isdesired to extend the saponification treatment over a considerableperiod of time, as for example from 10 minutes to many hours. Thus, forinstance, the high viscosity yarn may be built up into cakes in acentrifugal spinning box. These boxes may themselves be used for thesaponifying treatment in which case they should be made of or lined witha material reistant to alkali, as for example copper, or the cake may beremoved from the centrifugal spinning box, and while being supported onthe outside or inside or both be subjected to the saponifying treatment.Thus, for example, the cake removed from the box may be supported fromthe interior by means of a swift which may be made expansible forinsertion in the cake. Thus, for instance, the swift may comprise asmall end plate, the periphery of which is perforated with holes for theinsertion of a number of wires which after insertion in the interior ofthe cake may be expanded umbrella-fashion by means of a conical piecesliding on a shaft fitted to the end plate. Alternatively thecentrifugal spinning box before winding of the yarn therein may beprovided with a removable copper gauze lining in which the cake is builtup and in which it can be, removed from the spinning box. The cake withits supportinggauze outside may if necessary'be fitted with top andbottom plates to enable saponifying liquor to be circulated through thecake. Such a gauze may be used whether or not the cake is supported fromthe interior, as for example by means of the expansible swift referredto. Another means of supporting the cake from the interior consists inconstructing a number of small segmental gauzes to fit inside the cake,for example at opposite ends of two perpendicular diameters, the gauzebeing attached to each other in pairs by a spring distance piece. Such adevice is of value for supporting the interior of the cake whether ornot the cake is removed from the spinning box for saponification. Thesaponifying liquor maybe circulated through the cake, as for example bymeans of a pump, for the requisite time. In a similar manner thestretched yarn may be wound upon perforated bobbins or on a perforatedspool tube and the liquor circulated through the bobbin or otherpackage. In all such packages, whether of the bobbin, spool or caketype, it is sometimes advantageous to employ a cross wind with a quicktraverse so as to obtain a relatively porous package.

The following examples illustrate the invention but are not to beconsidered as limiting it in any way:

Example 1 Yarn dry-spun from cellulose acetate which has a viscosity of55 is wound on bobbins from which a creel is built up. The yarns are ledfrom the creel through a reed so as to constitute a warp, over the toproller, through the nip and under the bottom roller of a pair of hiprollers, the lower one of which is in advance of the upper one in thedirection of travel of the yarn and which dips into water acting as awetting out liquid. Thence the warp of yarns is carried out of thewetting out bath, over a further roller, down into the saponifyingliquor, through a reed and under a roller, thence the whole length ofthe saponifying bath which may be of the order of 90 feet long, througha further reed, close to a feed roller and out of the saponifying bathto suitable washing; drying and w.nding devices. The feed roller at theexit end of the saponifying bath is immersed less than half its diameterin the saponifying liquor. The saponifying bath consists of a 4%solution of caustic soda in a aqueous solution of sodium chloride and ismaintained at 85 C., and is circulated from end to end of the bath. Thespeed of travel of the filaments is 40 metres per minute. The threads,after treatment, have an increased tenacity and an increased extension.

.. Example 2 I The saponifying treatment is carried out as in Example 1with the exception that the saponifying liquor consists of a 5% solutionof caustic soda in a 25% aqueous solution of sodium chloride and ismaintained at 75 C. and the yarn is wet-spun from a cellulose acetatehaving a viscosity of 162 without applying substantial stretch.

Example 3 The saponifying treatment is carried out as in Example 1 withthe exception that the sodium chloride is replaced by sodium' acetate.

Example 4 The saponifying treatment is carried out as in Example 1 withthe exception that the saponifying bath consists of a 5.5% solution ofcaustic soda in a 25% aqueous solution of sodium chloride andismaintained at 75-90 C. and the yarn is made from a cellulose acetatehaving a viscosity of 120-180.

Example 5 Example 6 Yarn dry-spun from a cellulose acetate having aviscosity of 146 is put up into hank or cake form and is then treatedwith any of the following baths under the conditions stated:-

(a) 0.25% solution of caustic alkali in methyl alcohol in a bath volumeof 20:1 for 16 hours at (b) 0.5% solution of caustic alkali in. methylglscohol in a bath volume of 20:1 for 16 hours at (c) 0.5% solution ofcaustic alkali in methyl or ethyl alcohol in a bath volume of 40:1 for 4hours at C.

(d) 0.25% solution of caustic soda in ethyl alcohol in a bath volume of20:1 for 24 hours at In all the above examples the tenacity and theextension of the yarn are increased and the material acquires anafllnity for cotton colours. In Examples 1-4 the saponification issubstantially complete. In Example 5 the saponification correspondsclosely with the amount of caustic soda with which the yarn isimpregnated, and in Example 6 the degree of saponification varies withthe concentration of caustic soda and the time and temperature oftreatment.

In a similar manner the invention may be applied. to the production offilaments, threads, yarns and other materials from other saponifiablecellulose esters, for instance cellulose formate, cellulose propionateor cellulose butyrate. The cellulose esters may be present in thethreads, yarns or other materials either alone or mixedwith each otheror mixed with other materials not deleteriously affected by thetreatment, for instance natural or artificial cellulosic materials.

The cellulose esters present in the materials may be either simplecellulose esters as in the case of cellulose acetate, or mixed celluloseesters, for instance cellulose nitroacetate or mixed etheresters ofcellulose, for example oxyethyl cellulose acetate or ethyl celluloseacetate.

The materials in the form of filaments, threads, fabrics and the likemay in addition to the above treatments be subjected to a treatment withshrinking agents to improve their extension or for the production ofspecial effects, and in this connection reference is made broadly to theprocesses described in U. S. applications S. Nos. 611,240 filed May13th, 1932, 607,667 filed April 26th, 1932, and U. S. Patent No.2,020,303. Uniform shrinkage for the purpose of increasing extension isparticularly advantageous in the case of yarns which have relatively lowextensions. The shrinking treatment may be applied after saponification,but is preferably applied be- A fore. When applied before saponificationthe agents specified in the specifications referred to above may be usedwith advantage. Whenthe shrinking is applied subsequent tosaponification the nature of the reagent will depend upon the degree ofsaponification. Thus, if a relatively small degree has been applied,such as up to 10 or 20% loss in weight, swelling agents for thecellulose derivative may still be effective in producing the desiredshrinkage. When a high degree of saponiflcation or substantiallycomplete saponification has been carried out swelling agents forcellulose should be used toefl'eot the shrinkage.

'What I claim and desire to secure by Letters Patent is:

1. Process for the production of filaments, threads, yarns and the likehaving a relatively high tenacity and an afl'inity for cotton colors,which comprises subjecting to saponification dryspun filaments, threads,yarns or the like of acetone-soluble cellulose acetates having aviscosity exceeding 30 as measured by the rate of flow of a 6% acetonesolution against a standard. of glycerine as 100.

2. Process for the production of filaments, threads, yarns and the likehaving a relatively high tenacity and an affinity for cotton colors,which comprises subjecting filaments, threads, yarns or the like ofacetone-soluble cellulose acetates having a viscosity exceeding 30 asmeasured by the rate of flow of a 6% acetone solution against a standardof giycerine as 100, to saponification by-treating them with relativelyhigh concentrations of alkaline saponifying agents at temperatures notsubstantially below C. for not more than two minutes.

3. Process for the production of filaments, threads, yarns and the likehaving a relatively high tenacity and an ailinity for cotton colors,which comprises subjecting filaments, threads, yarns or the like ofacetone-soluble cellulose acetates having a viscosity exceeding 30 asmeasured by the rate of fiow 01. a 6% acetone solution against astandard of glycerine as 100, to saponification by treatment withrelatively high concentrations of an alkaline saponifying agent at atemperature above 60 C. in the presence of a buffer salt for not morethan two minutes.

4. Process for the production of filaments, threads, yarns and the likehaving a relatively high tenacity and an aifinity for cotton colors,which comprises subjecting filaments, threads, yarns or the like ofacetone-soluble cellulose acetates having a viscosity exceeding 30 asmeasured by the rate of flow of a 6% acetone solution against a standardof glycerine as 100, to saponification while they are traveling througha bath of the saponii'ying agent.

- HENRY DREYFUS.

CERTIFICATE OF CORRECTION.

Patent No. 2,053,767. SeptemberB, 1936 HENRY DREYFUS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 15, for the serial number "655,775" read 655,773, andsecond column, line 41, for "are" read as; and that the said LettersPatent should be read with these corrections therein that the same mayconform to the record .01 the case in the Patent Office.

Signed and sealed this 17th day of November, A. D. 1936.

He r Y n- 5mm (Seal)- Acting Commissioner of Patents.

